Shiisa Quilts gives you 40% off if you order 3 or more yards of select fabrics. I got some great Amy Butler Midwest Modern a few weeks ago to use as backing for a WIP that has been sitting for about a year now (terrible, I know!)
They offer very reasonable shipping to, so I totally recommend it if you want to stock up on some cheap yardage!
Another great resource I always use is a blog called Mommy Saves Big, they always have coupons you can print off and use at Joann Fabrics, this week there's a 50% off coupon and a 40% coupon (and yes, you can print off ten and send your husband and 8 kids in with you to buy others!!) I always use them on Kona yardage. While I love supporting my local quilt store's I can't justify passing up deals like this (that just means I can use that saved money towards designer fabric goodies!) The link for Joann's Printable Coupons is here.
(If you feel a lil uneasy using these, don't worry- they are the same coupons that get sent out if you are on Joann's email list). They have a ton of other coupons and online offers there too!